Solve for theta. cos ^2 theta -3 cos theta+2/sin ^2 theta =2
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sin^2 theta + cos theta = 2 (Use the Pythagorean identity sin^2 theta + cos^2 theta = 1 to replace sin^2 theta in the given equation).
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Step-by-step explanation:
Given, sin θ + 2cos θ = 1
Squaring on both sides, we get
Now, (sin θ + 2cos θ)2 = 12
=> sin2 θ + 4cos2 θ + 4*sin θ * cos θ = 1
=> 1 - cos2 θ + 4(1 - sin2 θ) + 4 * sin θ * cos θ = 1 [Since sin2 θ + cos2 θ = 1]
=> 1 - cos2 θ + 4 - 4 * sin2 θ + 4 * sin θ * cos θ = 1
=> 5 - cos2 θ - 4 * sin2 θ + 4 * sin θ * cos θ = 1
=> 5 - 1 = cos2 θ + 4 * sin2 θ - 4 * sin θ * cos θ
=> cos2 θ + 4 * sin2 θ - 4 * sin θ * cos θ = 4
=> 4 * sin2 θ + cos2 θ - 4 * sin θ * cos θ = 22
=> (2sin θ - cos θ)2 = 22
=> 2sin θ - cos θ = ±2
Hence proved
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